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This project is related to the manuscript "A global biogeographic regionalization of the benthic ocean", by Aurore A. Maureaud, Gabriel Reygondeau, Kate Ingenloff, Jessiva G. Vigneron, Les Watling, Kevin Winner, Walter Jetz.

International audience; Hotspots of tropical marine biodiversity are areas that harbour disproportionately large numbers of species compared to surrounding regions. The richness and location of these hotspots have changed throughout the Cenozoic. Here, we review the global dynamics of Cenozoic tropical marine biodiversity hotspots, including the four major hotspots of the Indo-Australian Archipelago (IAA), western Tethys (present Mediterranean), Arabian Sea and Caribbean Sea. Our review supports the ‘Hopping Hotspots’ model, which proposes that the locations of peak biodiversity are related to Tethyan faunal elements and track broad-scale shallow-marine habitats and high coastal complexity created by the collision of tectonic plates. A null hypothesis is the ‘Whack-A-Mole’ model, which proposes that hotspots occur in habitats suitable for high diversity regardless of taxonomic identity or faunal elements. Earlier ‘Centre-of’ theories (e.g. centres of origin with diversity decreasing with distance from supposed areas of exceptionally high rates of speciation, for which easy connection to adjacent regions to the east and west is important) were based on the analysis of recent biotas with no palaeontological foundation, and may better explain diversity dynamics within a hotspot rather than those between hotspots. More recently, however, human disturbance is massively disrupting these natural patterns.

We review the current knowledge of the biodiversity of the ocean as well as the levels of decline and threat for species and habitats. The lack of understanding of the distribution of life in the ocean is identified as a significant barrier to restoring its biodiversity and health. We explore why the science of taxonomy has failed to deliver knowledge of what species are present in the ocean, how they are distributed and how they are responding to global and regional to local anthropogenic pressures. This failure prevents nations from meeting their international commitments to conserve marine biodiversity with the results that investment in taxonomy has declined in many countries. We explore a range of new technologies and approaches for discovery of marine species and their detection and monitoring. These include: imaging methods, molecular approaches, active and passive acoustics, the use of interconnected databases and citizen science. Whilst no one method is suitable for discovering or detecting all groups of organisms many are complementary and have been combined to give a more complete picture of biodiversity in marine ecosystems. We conclude that integrated approaches represent the best way forwards for accelerating species discovery, description and biodiversity assessment. Examples of integrated taxonomic approaches are identified from terrestrial ecosystems. Such integrated taxonomic approaches require the adoption of cybertaxonomy approaches and will be boosted by new autonomous sampling platforms and development of machine-speed exchange of digital information between databases.

Climate change is impacting virtually all marine life. Adaptation strategies will require a robust understanding of the risks to species and ecosystems and how those propagate to human societies. We develop a unified and spatially explicit index to comprehensively evaluate the climate risks to marine life. Under high emissions (SSP5-8.5), almost 90% of similar to 25,000 species are at high or critical risk, with species at risk across 85% of their native distributions. One tenth of the ocean contains ecosystems where the aggregated climate risk, endemism and extinction threat of their constituent species are high. Climate change poses the greatest risk for exploited species in low-income countries with a high dependence on fisheries. Mitigating emissions (SSP1-2.6) reduces the risk for virtually all species (98.2%), enhances ecosystem stability and disproportionately benefits food-insecure populations in low-income countries. Our climate risk assessment can help prioritize vulnerable species and ecosystems for climate-adapted marine conservation and fisheries management efforts.

There has been a proliferation of climate change vulnerability assessments of species, yet possibly due to their limited reproducibility, scalability, and interpretability, their operational use in applied decision-making remains paradoxically low. We use a newly developed Climate Risk Index for Biodiversity to evaluate the climate vulnerability and risk for ∼2,000 species across three ecosystems and 90 fish stocks in the northwest Atlantic Ocean, a documented global warming hotspot. We found that harvested and commercially valuable species were at significantly greater risk of exposure to hazardous climate conditions than non-harvested species, and emissions mitigation disproportionately reduced their projected exposure risk and cumulative climate risk. Of the 90 fish stocks we evaluated, 41% were at high climate risk, but this proportion dropped to 25% under emissions mitigation. Our structured framework demonstrates how climate risk can be operationalized to support short- and long-term fisheries objectives to enhance marine fisheries’ climate readiness and resilience.

The future of the global ocean economy is currently envisioned as advancing towards a ‘blue economy’—socially equitable, environmentally sustainable and economically viable ocean industries1,2. However, tensions exist within sustainable development approaches, arising from differing perspectives framed around natural capital or social equity. Here we show that there are stark differences in outlook on the capacity for establishing a blue economy, and on its potential outcomes, when social conditions and governance capacity—not just resource availability—are considered, and we highlight limits to establishing multiple overlapping industries. This is reflected by an analysis using a fuzzy logic model to integrate indicators from multiple disciplines and to evaluate their current capacity to contribute to establishing equitable, sustainable and viable ocean sectors consistent with a blue economy approach. We find that the key differences in the capacity of regions to achieve a blue economy are not due to available natural resources, but include factors such as national stability, corruption and infrastructure, which can be improved through targeted investments and cross-scale cooperation. Knowledge gaps can be addressed by integrating historical natural and social science information on the drivers and outcomes of resource use and management, thus identifying equitable pathways to establishing or transforming ocean sectors1,3,4. Our results suggest that policymakers must engage researchers and stakeholders to promote evidence-based, collaborative planning that ensures that sectors are chosen carefully, that local benefits are prioritized, and that the blue economy delivers on its social, environmental and economic goals. The capacity to create an equitable and sustainable ‘blue economy’ from ocean resources will be determined by addressing social conditions, governance and infrastructure, not just resource availability, as shown by a fuzzy logic model incorporating multidisciplinary criteria.

Aim Project shifts in the habitat suitability of 505 fish and invertebrate species in the Eastern Tropical Pacific that are likely to occur by the mid-21st century under “high greenhouse gas emissions” (RCP 8.5) and “strong mitigation” (RCP 2.6) scenarios. Location The Eastern Tropical Pacific Ocean, a discrete biogeographic region from the Gulf of California to northern Peru. Methods Ensemble simulations of climate change effects on fish and invertebrate species caught by four major fisheries in the region, based on four species distribution models and three Earth system models. Results Simulation results indicated that species' habitat suitability increased or remained the same in the northern and southern margins of the Eastern Tropical Pacific but decreased by up to 14% in some fisheries along Central America. The largest declines in the average species habitat suitability index were projected for small pelagic fisheries (up to −46%), while the highest local species turnover was projected for coastal small-scale fisheries (up to 80%). Under RCP 8.5, species in the southern half and northern equatorial region of the Eastern Tropical Pacific were projected to shift south-east at a rate of approximately 30–60 km decade-1, respectively. Demersal species were projected to move into shallower, inshore waters with a shift in depth centroids estimated at a rate of around 1 to 13 m decade−1. Range shifts towards the equator reflect movements to cooler habitats that are characteristic of equatorial upwelling systems. Range shifts towards shallower, inshore waters reflect habitat compression associated with the expansion of oxygen minimum zones., SI

Regulatory boundaries and species distributions often do not align. This is especially the case for marine species crossing multiple Exclusive Economic Zones (EEZs). Such movements represent a challenge for fisheries management, as policies tend to focus at the national level, yet international collaborations are needed to maximize long-term ecological, social and economic benefits of shared marine species. Here, we combined species distributions and the spatial delineation of EEZs at the global level to identify the number of commercially exploited marine species that are shared between neighboring nations. We found that 67% of the species analyzed are transboundary (n = 633). Between 2005 and 2014, fisheries targeting these species within global-EEZs caught on average 48 million tonnes per year, equivalent to an average of USD 77 billion in annual fishing revenue. For select countries, over 90% of their catch and economic benefits were attributable to a few shared resources. Our analysis suggests that catches from transboundary species are declining more than those from non-transboundary species. Our study has direct implications for managing fisheries targeting transboundary species, highlighting the need for strengthened effective and equitable international cooperation.

Previous studies have focused on changes in the geographical distribution of terrestrial biomes and species targeted by marine capture fisheries due to climate change impacts. Given mariculture's substantial contribution to global seafood production and its growing significance in recent decades, it is essential to evaluate the effects of climate change on mariculture and their socio‐economic consequences. Here, we projected climate change impacts on the marine aquaculture diversity for 85 of the currently most commonly farmed fish and invertebrate species in the world's coastal and/or open ocean areas. Results of ensemble projections from three Earth system models and three species distribution models show that climate change may lead to a substantial redistribution of mariculture species richness potential, with an average of 10%–40% decline in the number of species being potentially suitable to be farmed in tropical to subtropical regions. In contrast, mariculture species richness potential is projected to increase by about 40% at higher latitudes under the ‘no mitigation policy’ scenario (RCP 8.5) by the mid‐21st century. In Exclusive Economic Zones where mariculture is currently undertaken, we projected an average future decline of 1.3% and 5% in mariculture species richness potential under RCP 2.6 (‘strong mitigation’) and RCP 8.5 scenarios, respectively, by the 2050s relative to the 2000s. Our findings highlight the opportunities and challenges for climate adaptation in the mariculture sector through the redistribution of farmed species and expansion of mariculture locations. Our results can help inform adaptation planning and governance mechanisms to minimize local environmental impacts and potential conflicts with other marine and coastal sectors in the future., We analysed the impacts of climate change on global mariculture species richness for 85 of the currently most commonly farmed species by the 2050s relative to the 2005s. Results of ensemble projections show that climate change may lead to a substantial redistribution of mariculture species richness potential, with an average of 10%–40% decline in the number of species being potentially suitable to be farmed in tropical to subtropical regions. In contrast, potential mariculture species diversity is projected to increase by about 40% at higher latitudes under the ‘no mitigation policy’ scenario (RCP 8.5) scenario by the mid‐21st century.

International audience; Sea water temperature affects all biological and ecological processes that ultimately impact ecosystem functioning. In this study, we examine the influence of temperature on global biomass transfers from marine secondary production to fish stocks. By combining fisheries catches in all coastal ocean areas and life history traits of exploited marine species, we provide global estimates of two trophic transfer parameters which determine biomass flows in coastal marine food web: the trophic transfer efficiency and the biomass residence time in the food web. We find that biomass transfers in tropical ecosystems are less efficient and faster than in areas with cooler waters. In contrast, biomass transfers through the food web became faster and more efficient between 1950 and 2010. Using simulated changes in sea water temperature from three Earth system models, we project that the mean trophic transfer efficiency in coastal waters would decrease from 7.7% to 7.2% between 2010 and 2,100 under the ‘no effective mitigation’ Representative Concentration Pathway (RCP 8.5), while biomass residence time between trophic level 2 and 4 is projected to decrease from 2.7 to 2.3 year on average. Beyond the global trends, we show that the trophic transfer efficiencies and biomass residence times may vary substantially among ecosystem types and that the polar ecosystems may be the most impacted ecosystems. The detected and projected changes in mean trophic transfer efficiency and biomass residence time will undermine food web functioning. Our study provides quantitative understanding of temperature effects on trophodynamic of marine ecosystems under climate change.

In this article, we analyze the impacts of climate change on Antarctic marine ecosystems. Observations demonstrate large-scale changes in the physical variables and circulation of the Southern Ocean driven by warming, stratospheric ozone depletion, and a positive Southern Annular Mode. Alterations in the physical environment are driving change through all levels of Antarctic marine food webs, which differ regionally. The distributions of key species, such as Antarctic krill, are also changing. Differential responses among predators reflect differences in species ecology. The impacts of climate change on Antarctic biodiversity will likely vary for different communities and depend on species range. Coastal communities and those of sub-Antarctic islands, especially range-restricted endemic communities, will likely suffer the greatest negative consequences of climate change. Simultaneously, ecosystem services in the Southern Ocean will likely increase. Such decoupling of ecosystem services and endemic species will require consideration in the management of human activities such as fishing in Antarctic marine ecosystems. Expected final online publication date for the Annual Review of Marine Science Volume 12 is January 3, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Climate change is shifting the distribution of shared fish stocks between neighboring countries' Exclusive Economic Zones (EEZs) and the high seas. The timescale of these transboundary shifts determines how climate change will affect international fisheries governance. Here, we explore this timescale by coupling a large ensemble simulation of an Earth system model under a high emission climate change scenario to a dynamic population model. We show that by 2030, 23% of transboundary stocks will have shifted and 78% of the world's EEZs will have experienced at least one shifting stock. By the end of this century, projections show a total of 45% of stocks shifting globally and 81% of EEZs waters with at least one shifting stock. The magnitude of such shifts is reflected in changes in catch proportion between EEZs sharing a transboundary stock. By 2030, global EEZs are projected to experience an average change of 59% in catch proportion of transboundary stocks. Many countries that are highly dependent on fisheries for livelihood and food security emerge as hotspots for transboundary shifts. These hotspots are characterized by early shifts in the distribution of an important number of transboundary stocks. Existing international fisheries agreements need to be assessed for their capacity to address the social-ecological implications of climate-change-driven transboundary shifts. Some of these agreements will need to be adjusted to limit potential conflict between the parties of interest. Meanwhile, new agreements will need to be anticipatory and consider these concerns and their associated uncertainties to be resilient to global change.El cambio climático está afectando la distribución de las poblaciones de fauna marina compartidas por Zonas Económicas Exclusivas (ZEEs) de países vecinos y en el alta mar. Los efectos del cambio climático en el manejo pesquero internacional estarán determinados por la escala temporal de dichos desplazamientos transfronterizos. Para determinar esa escala temporal, el presente estudio combinó un modelo dinámico poblacional, con una serie de simulaciones de un modelo del sistema terrestre, bajo un escenario de cambio climático de altas emisiones. Los resultados siguieren que para 2030, el 23% de las poblaciones transfronterizas se habrán desplazado y en el 78% de las ZEEs del mundo habrán experimentado cambios en la distribución de al menos una población transfronteriza. Para fines de este siglo, las proyecciones muestran que el 81% de las ZEEs tendrán al menos una población en movimiento y 45% de las poblaciones transfronterizas globales habrán cambiado su distribución. La magnitud de tal desplazamiento se reflejará en un cambio promedio del 59% de la proporción de captura de poblaciones transfronterizas entre ZEEs vecinas para el 2030. Muchos países que dependen de la pesca para sustento económico y seguridad alimentaria emergen como zonas críticas de cambios transfronterizos. Estas zonas se caracterizan por cambios tempranos en la distribución de un número importante de poblaciones transfronterizas. Por lo tanto, los acuerdos pesqueros internacionales deben evaluarse por su capacidad para responder a los impactos socio-ecológicos del desplazamiento de poblaciones transfronterizas debido al cambio climático. Dichos acuerdos deberán de ser ajustados para limitar los posibles conflictos entre las partes de interés y evitar amenazar la sustentabilidad del recurso. Así mismo, los nuevos acuerdos que vayan a establecerse deberán considerar los posibles cambios en la distribución de poblaciones compartidas (y la incertidumbre asociada) para anticiparse a dichos conflictos y aumentar la resiliencia frente al cambio climático.Le changement climatique altère la distribution des stocks de poissons exploités posant de sérieux problèmes de juridiction et gestion des espèces partagées entre pays voisins, et/ou avec la haute mer. C’est en analysant l’échelle de temps de ces migrations transfrontalières que l’impact du changement climatique sur la gouvernance mondiale des pêches peut être évalué. Dans cette étude, nous explorons cette échelle de temps à l'aide d’un modèle de dynamique des populations marines exploitées couplé à des simulations dérivées d’un ensemble de modèles globaux océan-atmosphère. Les résultats montrent que d’ici 2030, pour le scénario à hautes émissions, 23% des stocks transfrontaliers auront changé de distribution et que 78% des zones économiques exclusives (ZEE) expérimenteront au moins une nouvelle espèce transfrontalière. A la fin du siècle, et pour ce même scénario, 81% des ZEE auront au moins une espèce transfrontalière et 45% des stocks transfrontaliers auront changé de distribution. La magnitude de tels changements de distribution est ici quantifiée par la variation dans la proportion de capture entre ZEE partageant ce stock transfrontalier. D’ici 2030, de tels changements entre ZEE seront de l’ordre de 59% à l'échelle globale, avec de nombreux pays dont la qualité de vie et la sécurité alimentaire dépendent de la pêche émergeant comme zones à haut risque. Ces zones se caractérisent par le déplacement précoce d’un grand nombre de stocks transfrontaliers. A la lumière de ces résultats, les traités et accords de pêche internationaux doivent être évalués pour leur capacité à répondre aux implications socio-écologiques du changement climatique et renégocier afin d’éviter tout conflit entre pays voisins. En anticipant des changements potentiels de distribution entre stocks transfrontaliers, tout nouvel accord de pêche se voudra plus résilient aux effets du changement climatique.As mudanças climáticas vêm promovendo alterações na distribuição dos estoques de peixes compartilhados por países vizinhos, tanto nas suas Zonas Econômicas Exclusivas (ZEE) como em águas oceânicas internacionais. A escala de tempo desse deslocamento transfronteiriço vai determinar como as mudanças climáticas afetarão o manejo pesqueiro internacional. Diante disso, o presente trabalho teve por objetivo analisar essa escala de tempo, combinando um amplo conjunto de simulações de um modelo do sistema terrestre sob um cenário de mudanças climáticas de altas emissões a um modelo de dinâmica populacional. Foi observado que, para 2030, 23% dos estoques transfronteiriços terão suas distribuições alteradas e 78% das ZEEs do mundo terão experimentado deslocamentos em pelo menos um estoque transfronteiriço. No final deste século, as projeções mostram que 45% dos estoques transfronteiriços do mundo sofrerão alterações e que 81% das ZEEs apresentarão alterações em pelo menos um estoque. A magnitude de tal deslocamento será refletida por uma mudança média de 59% na proporção de capturas de estoques transfronteiriços entre ZEEs vizinhas no ano de 2030. Muitos países que são altamente dependentes da pesca para subsistência e segurança alimentar surgem como pontos críticos para mudanças transfronteiriças. Estes são caracterizados por mudanças iniciais na distribuição de um número importante de estoques transfronteiriços. Os acordos internacionais de pesca precisam ser avaliados quanto à sua capacidade de abordar as implicações sócio-ecológicas de deslocamentos transfronteiriços impulsionados pelas mudanças climáticas e ajustados para limitar um possível conflito entre as partes de interesse. Da mesma forma, novos acordos devem considerar possíveis mudanças na distribuição de populações transfronteiriças a fim de antecipar tais conflitos e construir resiliência em face das mudanças climáticas e das incertezas que as acompanha.

We review the current knowledge of the biodiversity of the ocean as well as the levels of decline and threat for species and habitats. The lack of understanding of the distribution of life in the ocean is identified as a significant barrier to restoring its biodiversity and health. We explore why the science of taxonomy has failed to deliver knowledge of what species are present in the ocean, how they are distributed and how they are responding to global and regional to local anthropogenic pressures. This failure prevents nations from meeting their international commitments to conserve marine biodiversity with the results that investment in taxonomy has declined in many countries. We explore a range of new technologies and approaches for discovery of marine species and their detection and monitoring. These include: imaging methods, molecular approaches, active and passive acoustics, the use of interconnected databases and citizen science. Whilst no one method is suitable for discovering or detecting all groups of organisms many are complementary and have been combined to give a more complete picture of biodiversity in marine ecosystems. We conclude that integrated approaches represent the best way forwards for accelerating species discovery, description and biodiversity assessment. Examples of integrated taxonomic approaches are identified from terrestrial ecosystems. Such integrated taxonomic approaches require the adoption of cybertaxonomy approaches and will be boosted by new autonomous sampling platforms and development of machine-speed exchange of digital information between databases.

Extreme temperature events have occurred in all ocean basins in the past two decades with detrimental impacts on marine biodiversity, ecosystem functions, and services. However, global impacts of temperature extremes on fish stocks, fisheries, and dependent people have not been quantified. Using an integrated climate-biodiversity-fisheries-economic impact model, we project that, on average, when an annual high temperature extreme occurs in an exclusive economic zone, 77% of exploited fishes and invertebrates therein will decrease in biomass while maximum catch potential will drop by 6%, adding to the decadal-scale mean impacts under climate change. The net negative impacts of high temperature extremes on fish stocks are projected to cause losses in fisheries revenues and livelihoods in most maritime countries, creating shocks to fisheries social-ecological systems particularly in climate-vulnerable areas. Our study highlights the need for rapid adaptation responses to extreme temperatures in addition to carbon mitigation to support sustainable ocean development.

Climate change is shifting the distribution of shared fish stocks between neighboring countries’ Exclusive Economic Zones (EEZ) and the high seas. The timescale of these transboundary shifts determines how climate change will affect international fisheries governance. Coupling a large ensemble simulation of an Earth system model to a species distribution model, we show that by 2030, 23% of transboundary stocks would have shifted and 78% of the world EEZs will experience at least one shifting stock under a high emission climate change scenario. By the end of this century, 81% of EEZ waters will see at least one shifting stock with a total of 45% of stocks shifting globally, under a high emissions scenario. Importantly, many countries that are highly dependent on fisheries for income, food and nutrition security, as well as livelihoods emerge as hotspots for transboundary shifts showing early, and sometimes past shifts. Existing fisheries agreements need to be assessed for their capacity in addressing transboundary shifts, and strengthened where necessary to limit conflict over these fish stocks while new agreements are urged to considere this problematic in order to be resilient to global change.

International audience; Climate change impacts on marine life in the world ocean are expected to accelerate over the 21st century, affecting the structure and functioning of food webs. We analyzed a key aspect of this issue, focusing on the impact of changes in biomass flow within marine food webs and the resulting effects on ecosystem biomass and production. We used a modeling framework based on a parsimonious quasi-physical representation of biomass flow through the food web, to explore the future of marine consumer biomass and production at the global scale over the 21st century. Biomass flow is determined by three climate-related factors: primary production entering the food web, trophic transfer efficiency describing losses in biomass transfers from one trophic level (TL) to the next, and flow kinetic measuring the speed of biomass transfers within the food web. Using climate projections of three earth system models, we calculated biomass and production at each TL on a 1 degrees latitude x1 degrees longitude grid of the global ocean under two greenhouse gas emission scenarios. We show that the alterations of the trophic functioning of marine ecosystems, mainly driven by faster and less efficient biomass transfers and decreasing primary production, would lead to a projected decline in total consumer biomass by 18.5% by 2090-2099 relative to 1986-2005 under the "no mitigation policy" scenario. The projected decrease in transfer efficiency is expected to amplify impacts at higher TLs, leading to a 21.3% decrease in abundance of predators and thus to a change in the overall trophic structure of marine ecosystems. Marine animal production is also projected to decline but to a lesser extent than biomass. Our study highlights that the temporal and spatial projected changes in biomass and production would imply direct repercussions on the future of world fisheries and beyond all services provided by Ocean.

Sustainably managed wild fisheries support food and nutritional security, livelihoods, and cultures (1). Harmful fisheries subsidies—government payments that incentivize overcapacity and lead to overfishing—undermine these benefits yet are increasing globally (2). World Trade Organization (WTO) members have a unique opportunity at their ministerial meeting in November to reach an agreement that eliminates harmful subsidies (3). We—a group of scientists spanning 46 countries and 6 continents—urge the WTO to make this commitment...

Progress in global shark conservation has been limited by constraints to understanding the species composition and geographic origins of the shark fin trade. Previous assessments that relied on earlier genetic techniques and official trade records focused on abundant pelagic species traded between Europe and Asia. Here, we combine recent advances in DNA barcoding and species distribution modelling to identify the species and source the geographic origin of fins sold at market. Derived models of species environmental niches indicated that shark fishing effort is concentrated within Exclusive Economic Zones, mostly in coastal Australia, Indonesia, the United States, Brazil, Mexico and Japan. By coupling two distinct tools, barcoding and niche modelling, our results provide new insights for monitoring and enforcement. They suggest stronger local controls of coastal fishing may help regulate the unsustainable global trade in shark fins.

Natural and human stressors in the high seas act across a wide range of spatial and temporal scales. These include direct interaction such as fisheries bycatch or indirect interaction like warming oceans and plastic ingestion. Area-based management tools (ABMTs), such as marine protected areas and time-area closures, are a widely accepted and a broadly successful form of management used to mitigate localized human impacts on marine species and ecosystems. Protection provides an opportunity for population recovery, which can then propagate outside of the closure. As the United Nations negotiates a new treaty on the conservation and sustainable use of biodiversity beyond national jurisdiction, efforts to design and implement high seas ABMTs at appropriate scales are critical to ensure that these spatial protection measures are most effective and climate-ready in the face of changing oceans. Here we identify the four most important temporal scales – contemporary, intra-annual, multi-annual and multidecadal – for aligning high seas ABMTs to relevant ecological, oceanographic and atmospheric processes. From this, we explore how managers and decision-makers can integrate this knowledge when implementing a new treaty.

The future of the global ocean economy is currently envisioned as advancing towards a 'blue economy'-socially equitable, environmentally sustainable and economically viable ocean industries

WOS:000579835900001; International audience; The global ocean is commonly partitioned into 4 biomes subdivided into 56 biogeochemical provinces (BGCPs) following the accepted partition proposed by Longhurst in 1998. Each province corresponds to a unique regional environment that shapes biodiversity and constrains ecosystem structure and functions. BGCPs are dynamic entities that change their spatial extent and position with climate and are expected to be pertubated in the near future by global climate change. Here, we characterize the changes in spatial distribution of BGCPs from 1950 to 2100 using three earth system models under two representative concentration pathways (RCP 2.6 and 8.5). We project a reorganisation of current distribution of BGCPs driven mostly by a poleward shift of their distributions (18.4 km in average per decade). Projection of the future distribution of BGCPs also revealed the emergence of new climate that has no analogue with past and current environmental conditions experienced by BGCPs . This novel environmental conditions, here named No-Analogue BGCPs State (NABS), will expand from 2040 to 2100 at a rate of 4.3 Mkm2 per decade (1.2% of the global ocean). We subsequently quantified the potential amount of marine species and fisheries catch that would experience such novel environmental conditions to roughly evaluate NABS impact on ecosystem services.

Risk of impact of marine fishes to fishing and climate change (including ocean acidi- fication) depend on the species’ ecological and biological characteristics, as well as their exposure to over‐exploitation and climate hazards. These human‐induced haz- ards should be considered concurrently in conservation risk assessment. In this study, we aim to examine the combined contributions of climate change and fishing to the risk of impacts of exploited fishes, and the scope for climate‐risk reduction from fisheries management. We combine fuzzy logic expert system with species dis- tribution modeling to assess the extinction risks of climate and fishing impacts of 825 exploited marine fish species across the global ocean. We compare our calcu- lated risk index with extinction risk of marine species assessed by the International Union for Conservation of Nature (IUCN). Our results show that 60% (499 species) of the assessed species are projected to experience very high risk from both over- fishing and climate change under a “business‐as‐usual” scenario (RCP 8.5 with cur- rent status of fisheries) by 2050. The risk index is significantly and positively related to level of IUCN extinction risk (ordinal logistic regression, p20%) chance of having high extinction risk in the next few dec- ades (equivalent to the IUCN categories of vulnerable, endangered or critically endangered). Areas with more at‐risk species to climate change are in tropical and subtropical oceans, while those that are at risk to fishing are distributed more broadly, with higher concentration of at‐risk species in North Atlantic and South Pacific Ocean. The number of species with high extinction risk would decrease by 63% under the sustainable fisheries‐low emission scenario relative to the “business ‐as‐usual” scenario. This study highlights the substantial opportunities for climate ‐risk reduction through effective fisheries management.

The increase in anthropogenic CO 2 emissions over the last century has modified oceanic conditions, affecting marine ecosystems and the goods and services that they provide to society. Pacific Island countries and territories are highly vulnerable to these changes because of their strong dependence on ocean resources, high level of exposure to climate effects, and low adaptive capacity. Projections of mid-to-late 21st century changes in sea surface temperature (SST), dissolved oxygen, pH, and net primary productivity (NPP) were synthesized across the tropical Western Pacific under strong climate mitigation and business-as-usual scenarios. These projections were used to model impacts on marine biodiversity and potential fisheries catches. Results were consistent across three climate models, indicating that SST will rise by ≥ 3 °C, surface dissolved oxygen will decline by ≥ 0.01 ml L −1 , pH will drop by ≥ 0.3, and NPP will decrease by 0.5 g m −2 d −1 across much of the region by 2100 under the business-as-usual scenario. These changes were associated with rates of local species extinction of > 50% in many regions as fishes and invertebrates decreased in abundance or migrated to regions with conditions more suitable to their bio-climate envelope. Maximum potential catch (MCP) was projected to decrease by > 50% across many areas, with the largest impacts in the western Pacific warm pool. Climate change scenarios that included strong mitigation resulted in substantial reductions of MCP losses, with the area where MCP losses exceeded 50% reduced from 74.4% of the region under business-as-usual to 36.0% of the region under the strong mitigation scenario.

In several Pacific Island countries and territories (PICTs), rapid population growth and inadequate management of coastal fish habitats and stocks is causing a gap to emerge between the amount of fish recommended for good nutrition and sustainable harvests from coastal fisheries. The effects of ocean warming and acidification on coral reefs, and the effects of climate change on mangrove and seagrass habitats, are expected to widen this gap. To optimise the contributions of small-scale fisheries to food security in PICTs, adaptations are needed to minimise and fill the gap. Key measures to minimise the gap include community-based approaches to: manage catchment vegetation to reduce sedimentation; maintain the structural complexity of fish habitats; allow landward migration of mangroves as sea level rises; sustain recruitment and production of demersal fish by managing ‘source’ populations; and diversify fishing methods to increase catches of species favoured by climate change. The main adaptions to help fill the gap in fish supply include: transferring some fishing effort from coral reefs to tuna and other large pelagic fish by scaling-up the use of nearshore fish aggregating devices; developing fisheries for small pelagic species; and extending the shelf life of catches by improving post-harvest methods. Modelling the effects of climate change on the distribution of yellowfin tuna, skipjack tuna, wahoo and mahi mahi, indicates that these species are likely to remain abundant enough to implement these adaptations in most PICTs until 2050. We conclude by outlining the policies needed to support the recommended adaptations.

Ocean warming and deoxygenation are affecting the physiological performance of marine species by increasing their oxygen demand while reducing oxygen supply. Impacts on organisms (e.g., growth and reproduction) can eventually affect entire populations, altering macroecological dynamics and shifting species’ distribution ranges. To quantify the effect of warming and deoxygenation on marine organisms, Penn et al. (2018) and Deutsch et al. (2020) developed two metabolic indices that integrate physiological, biogeographic and climatic data. Here, we develop an alternative index, referred to as Aerobic Growth Index (AGI) based on an approach that integrates the von Bertalanffy growth and metabolic theory. We compare the results derived from the application of AGI with those of the two previously published metabolic indices for six species: Atlantic blue crab (Callinectes sapidus), sharpsnout seabream (Diplodus puntazzo), Atlantic cod (Gadus morhua), Australian spiny lobster (Panulirus cygnus), red drum (Sciaenops ocellatus) and common cuttlefish (Sepia officinalis). The baseline (1971–2000) habitat suitability values of AGI are significantly and positively correlated with both metabolic indices (R2 ≥ 0.92). All three indices also show similar spatial patterns and magnitudes of viable habitat loss by the end of the 21st century (2071–2100) relative to baseline conditions under a high greenhouse gas trajectory (Representative Concentration Pathway 8.5). Our results support the applicability and use of AGI to better understand the impacts of warming and deoxygenation on global marine fishery resources. Given the uncertainties surrounding mechanisms linking temperature, oxygen and biogeography, there is a need for different indicators to account for these uncertainties in climate change projections.

Aim Following the biogeographical approach implemented by Longhurst for the epipelagic layer, we propose here to identify a biogeochemical 3-D partition for the mesopelagic layer. The resulting partition characterizes the main deep environmental biotopes and their vertical boundaries on a global scale, which can be used as a geographical and ecological framework for conservation biology, ecosystem-based management and for the design of oceanographic investigations. Location The global ocean. Methods Based on the most comprehensive environmental climatology available to date, which is both spatially and vertically resolved (seven environmental parameters), we applied a combination of clustering algorithms (c-means, k-means, partition around medoids and agglomerative with Ward's linkage) associated with a nonparametric environmental model to identify the vertical and spatial delineation of the mesopelagic layer. Results First, we show via numerical interpretation that the vertical division of the pelagic zone varies and, hence, is not constant throughout the global ocean. Indeed, a latitudinal gradient is found between the epipelagic–mesopelagic and mesopelagic–bathypelagic vertical limits. Second, the mesopelagic layer is shown here to be composed of 13 distinguishable Biogeochemical Provinces. Each province shows a distinct range of environmental conditions and characteristic 3-D distributions. Main conclusions The historical definition of the mesopelagic zone is here revisited to define a 3-D geographical framework and characterize all the deep environmental biotopes of the deep global ocean. According to the numerical interpretation of mesopelagic boundaries, we reveal that the vertical division of the zone is not constant over the global ocean (200–1,000 m) but varies between ocean basin and with latitude. We also provide evidence of biogeochemical division of the mesopelagic zone that is spatially structured in a similar way than the epipelagic in the shallow waters but varies in the deep owing to a change of the environmental driving factors.

Understanding the distribution of life’s variety has driven naturalists and scientists for centuries, yet this has been constrained both by the available data and the models needed for their analysis. Here we compiled data for over 67,000 marine and terrestrial species and used artificial neural networks to model species richness with the state and variability of climate, productivity, and multiple other environmental variables. We find terrestrial diversity is better predicted by the available environmental drivers than is marine diversity, and that marine diversity can be predicted with a smaller set of variables. Ecological mechanisms such as geographic isolation and structural complexity appear to explain model residuals and also identify regions and processes that deserve further attention at the global scale. Improving estimates of the relationships between the patterns of global biodiversity, and the environmental mechanisms that support them, should help in efforts to mitigate the impacts of climate change and provide guidance for adapting to life in the Anthropocene.

Quantifying species spatial distribution and biodiversity patterns represents one of the pillars of ecology. The ocean and human society are in a closed interaction loop, with the ocean providing benefits such as food provision and humans influencing the natural state of the ocean either by direct pressures such as fisheries or indirect pressures such as modification of climate. Ecosystem services provided by the ocean are structured at local or regional scales by the biodiversity pool of species occurring, which define the trophodynamics of the ecosystem. Therefore the study of species distributions and their interactions allows for the characterization of ecosystem functioning and the quantification of the potential benefits of the ocean to human society. The discipline of biogeography is defined as: “The study of the spatial distributions of organisms, both past and present, understanding all patterns of geographic variation in nature—from genes to entire communities and ecosystems—elements of biological diversity that vary across geographic gradients including those of area, isolation, latitude, depth, and elevation.”

In high-latitude marine environments, primary producers and their consumers show seasonal peaks of abundance in response to annual light cycle, water column stability and nutrient availability. Predatory species have adapted to this pattern by synchronising life-history events such as reproduction with prey availability. However, changing temperatures may pose unprecedented challenges by decoupling the predator-prey interactions. Here we build a predator-prey model accounting for the full life-cycle of fish and zooplankton including their phenology. The model assumes that fish production is bottom-up controlled by zooplankton prey abundance and match or mismatch between predator and prey phenology, and is parameterised based on empirical findings of how climate influences phenology and prey abundance. With this model, we project possible climate-warming effects on match-mismatch dynamics in Arcto-boreal and temperate biomes. We find a strong dependence on synchrony with zooplankton prey in the Arcto-boreal fish population, pointing towards a possible pronounced population decline with warming because of frequent desynchronization with its zooplankton prey. In contrast, the temperate fish population appears better able to track changes in prey timing and hence avoid strong population decline. These results underline that climate change may enhance the risks of predator-prey seasonal asynchrony and fish population declines at higher latitudes. Contrasting effects of rising temperatures on trophic interactions in marine ecosystems

Climate change is impacting marine ecosystems and their goods and services in diverse ways, which can directly hinder our ability to achieve the Sustainable Development Goals (SDGs), set out under the 2030 Agenda for Sustainable Development. Through expert elicitation and a literature review, we find that most climate change effects have a wide variety of negative consequences across marine ecosystem services, though most studies have highlighted impacts from warming and consequences of marine species. Climate change is expected to negatively influence marine ecosystem services through global stressors—such as ocean warming and acidification—but also by amplifying local and regional stressors such as freshwater runoff and pollution load. Experts indicated that all SDGs would be overwhelmingly negatively affected by these climate impacts on marine ecosystem services, with eliminating hunger being among the most directly negatively affected SDG. Despite these challenges, the SDGs aiming to transform our consumption and production practices and develop clean energy systems are found to be least affected by marine climate impacts. These findings represent a strategic point of entry for countries to achieve sustainable development, given that these two goals are relatively robust to climate impacts and that they are important pre‐requisite for other SDGs. Our results suggest that climate change impacts on marine ecosystems are set to make the SDGs a moving target travelling away from us. Effective and urgent action towards sustainable development, including mitigating and adapting to climate impacts on marine systems are important to achieve the SDGs, but the longer this action stalls the more distant these goals will become.

The global ocean is projected to be warmer, less oxygenated and more acidic in the 21st century relative to the present day, resulting in changes in the biogeography and productivity of marine organisms and ecosystems. Previous studies using a Dynamic Bioclimate Envelope Model (DBEM) projected increases in potential catch in high latitude regions and decreases in tropical regions over the next few decades. A major structural uncertainty of the projected redistribution of species and fisheries catches can be attributed to the habitat suitability algorithms used. Here, we compare the DBEM projections of potential catches of 500 species of exploited marine fishes and invertebrates from 1971 to 2060 using three versions of DBEM that differ by the algorithm used to predict relative habitat suitability: DBEM-Basic, DBEM-Maxent and DBEM-Aquamaps. All the DBEM models have similar skill in predicting the occurrence of exploited species and distribution of observed fisheries production. Globally, the models project a decrease in catch potential of 3% to 13% by 2050 under a high emissions scenario (Representative Concentration Pathway 8.5). For the majority of the modelled species, projections by DBEM-Maxent are less sensitive to changes in ocean properties than those by DBEM-Aquamaps. The mean magnitude of projected changes relative to differences between projections differ between regions, being highest (>1 times the standard deviation) in the tropical regions and Arctic Ocean and lowest in three of the main Eastern Boundary Upwelling regions, the eastern Indian Ocean and the Southern Ocean. These results suggest that the qualitative patterns of changes in catch potential reported in previous studies are not affected by the structural uncertainty of DBEM, particularly in areas where catch potential was projected to be most sensitive to climate change. However, when making projections of fish stocks and their potential catches using DBEM in the future, multiple versions of DBEM should be used to quantify the uncertainty associated with structural uncertainty of the models. Overall, this study contributes to improving projection of future changes in living marine resources by exploring one aspect of the cascade of uncertainty associated with such projections.

Natural and human stressors in the high seas act across a wide range of spatial and temporal scales. These include direct interaction such as fisheries bycatch or indirect interaction like warming oceans and plastic ingestion. Area-based management tools (ABMTs), such as marine protected areas and time-area closures, are a widely accepted and a broadly successful form of management used to mitigate localized human impacts on marine species and ecosystems. Protection provides an opportunity for population recovery, which can then propagate outside of the closure. As the United Nations negotiates a new treaty on the conservation and sustainable use of biodiversity beyond national jurisdiction, efforts to design and implement high seas ABMTs at appropriate scales are critical to ensure that these spatial protection measures are most effective and climate-ready in the face of changing oceans. Here we identify the four most important temporal scales – contemporary, intra-annual, multi-annual and multidecadal – for aligning high seas ABMTs to relevant ecological, oceanographic and atmospheric processes. From this, we explore how managers and decision-makers can integrate this knowledge when implementing a new treaty.